Revisting Tag Collision Problem in RFID Systems

In RFID systems, the reader is unable to discriminate concurrently reported IDs of tags from the overlapped signals, and a collision happens. Many algorithms for anticollision are proposed to improve the throughput and reduce the latency for tag identification. Existing anti-collision algorithms mainly employ CRC based collision detection functions for determining whether the collision happens. Generating CRC codes, however, requires complicated computations for both RF tags and readers, and hence incurs non-trivial time consumption, becoming the bottleneck. In this study, we design a Quick Collision Detection (QCD) scheme based on the bitwise complement function plus collision preamble, which significantly reduces the number of gates for computation and facilitates to simplify the IC design of RFID tags. The QCD scheme does not require any modification on upperlevel air protocols, so it can be seamlessly adopted by current anti-collision algorithms. Through comprehensive analysis and simulations, we show that QCD improves the identification efficiency by 40%.